A senior American diplomat has assured Afghan leaders that Washington’s commitment to the war-torn country's peace, prosperity and security will only deepen under the incoming administration of President-elect Donald Trump.

Under Secretary of State for Political Affairs Thomas Shannon traveled to Kabul Saturday, where he met with President Ashraf Ghani, Chief Executive Abdullah Abdullah, and other senior government officials.

Shannon later told reporters the purpose of his visit was to underscore the strong partnership the two countries have been able to build during eight years of outgoing U.S. President Barack Obama.

“(But) our commitment to Afghanistan does not end on January 20 (when Trump will take the oath of office), quite the contrary it will only deepen and that the strategic importance of this relationship is evident to all,” emphasized Shannon.

“I can assure you that our purpose and intention here is enduring, is sustainable and its long term,” added Shannon.

It is unclear how President-elect Trump plans to deal with operations in Afghanistan, which have become America’s longest war.

Around 8,500 American troops are in Afghanistan, training, advising and assisting local forces in their battle against the resurgent Taliban.

The U.S. military mission is also tasked with conducting anti-terrorism operations against al-Qaida and Islamic State terrorists in the country.

Under Secretary Shannon visited Kabul a day after the U.S. Marine Corps announced that it will send a new task force of around 300 military advisors to the southern Afghan province of Helmand later this year.

The Taliban has overrun most of the districts of the poppy-producing region after NATO withdrew forces from Afghanistan two years ago. The insurgents have also made battlefield gains elsewhere in the country and there are fears of more violence during 2017.

According to the U.S. military, the Afghan government currently is in control of some 64 percent of the population while around 10 percent is controlled by the Taliban and the rest is contested.